Process of making pulp



Penman: 18, 1929.

UNITED STATES I 1,717,798 PATENT o1=1=1c1-:.

ROBERTA. MARE, OF NORFOLK, VIRGINIA.

PROCESS OF MAKING- PULP.

Io Drawing. Application filed latch 27, 1924, Serial No.v 702,442.Renewed March 15, 1929.

The present invention relates to the production of pulp and pulp roductsfrom wood and other cellulosic an ligneous material, and the process isapplicable to all 8 kinds of wood, including woods that are hard, soft,porous, non-porous, also other equivalent materials e, g. cane, bamboo,straw, sedges and other marsh growth, banana stalks, cocoanut husks andthe like.

The process consists essentially in first boiling the wood in a solutioncontaining sodium nitrate or other nitrate of an alkaliforming metal,such as potassium nitrate, calcium nitrate, magnesium nitrate, althoughother nitrates can be employed, and it is not by intention to restrictthe present case to the use of a particular nitrate or a group of suchnitrates. However, the nitrates of the alkali-forming metals areenerally cheaper and somewhat more satis actory than an other nitratewith which I have experimented. After the material has been in thesolution of nitrate, the same is removed from the solution, is preferablsoaked for a time in coldwater, after whic it is run through pressurerolls or otherwise crushed and is then run throu h a pulper, with water,and is then preferab run into a beater in which it is beaten, pre erablywith the roll raised a substantial distance above the bed-plate, (3 to 5turns) after which it may be sheeted or a ortion of the cementitiousmatter ma first be removed from the pulped materia either before, duringor after the beatin operation, before being converted into s eets. Thepulp can be produced converted into sheets in the form of paper orcardboard or it can be converted into other shaped articles, in a mannerwell understood in the art.

is to be understood that they are .given merely for the purpose ofillustration and not as restrictin the invention thereto.

Ewample 1.-- looks of spruce in a dried say 40% of water, and blocks ofyellow oplar were introduced into a digester sue as is used in makingpulp by the well known processes, includin the soda process, sulphiteprocess and t e like, suflicient of the solution being used tocompletely cover the woody material. The mass was then heated until apressure of about 110 lbs, existed in the digester, which condition wascontinued for about an hour, after which the solution was allowed tocool more or less and The following examples are given, but it.

condition, chips of spruce containing about the material removed fromthe digester. The total time that the pressure was above 80 lbs. in thedigester was considered as the effective cooking period, this amountingto two hours.

The treated material was then removed from the digester' li uor, wasplaced in a tank of cold water, 'or several hours and the materials werethen run through crushing rollers, then with water through a pulper, andinto a beater. The beating was commenced with the roll of the beaterraised about six turns above the bed, and the roll was gradually loweredto about 3 turns of the bed. The beating was continued for half an hour,after which a portion of the pulp was sheeted and-dried Without washing.An-

other portion of the pul was first washed, being given a light was ing,with a spray of water, and was then sheeted. Another portion was furtherbeaten for half an hour and sheeted. Another portion was further beatenfor half an hour, at about the end of the beating operation, size andalum were added in the amounts commonly used in sizing paper. In otherinstances portions of the pulp were washed and then sized, and thensheeted.

Ewample 2.-Blocks of spruce wood, in a substantially air dry state wereplaced in the liquor remaining from the above treatment, and heatapplied. About three-quarters of an hour were necessary before thepressure reached one hundred pounds and the pressure was maintained atone hundred pounds for about an hour, after which the liquor was allowedto cool somewhat and the blocks removed from the digester and placed incold water overnight. The followin day these were worked up as aboveindicate E'mample- 3.-Blocks of air dr spruce wood, spruce wood in theform of c ips contaming about 40% of moisture, yellow poplar and greencane were placed in the solution'remaining from the above experiment myexperiments indicate that the solution can be used a very great numberof times before the same becomes sufliciently impureto make it necessaryto discard the same. The heating of the solution, by blowing in steam,will of course dilute the solution to a certain extent, and it isaccordingly advisable after each fourth or fifth cook, to add a littlemore nitrate, in order to bring tllie stirength back to that originallyemp oye The sheeted products resulting frpm' the treatment of sprucewood were of a light but? color. All of the sheeted material produced inthe above ex eriments was found to be very strong, simi ar to kraft paer of the best grade. The product'produce from poplar wood was of asubstantially darker color than that produced from spruce, being 0 amedium brown. This product was particularly strong and tough and wasadapted for very strong wrapping paper.

During the cooking operation, the liquor acquires a yellowish color andis found to have a pronounced'caramel odor.

My experiments indicate that something over 95% of the dry matter of thewood can be recovered in the form of unwashed pulp, but it is to beunderstood that any de- 3 sired proportion of the cementitious mattercan be washed out after the pulpin o eration, either before during orafter t e eating operation. The cementitious matter thus washed out canbe recovered and can be used in making various plastic shaped articles.

The use of nitrates seems in some respects to be somewhat better thansulfates as referred to in some of mycopending applica- 40 tions, andalso seems to, be somewhat better than sodium chloride referred to inanother copendlng aplpllcation of mine. From the same wood, t e pulpproduct produced when mtrate forms the dlgestive solution, seems to besomewhat tougher and stronger than the solution used in sodium chloride.

The ulp produced can be used not onl for ma mg paper and other similarprod ucts, but for makmg cardboard and various molded articles.

While I have above referred to the use of a solution of 1.6%, it is tobe understood that the product.

It will be observed that while in many of the pulp-making processesheretofore, used 1n the country, it has been customary to boil the woodor other material under high pres- 5 sure untll the same has beenconverted into a pulp, and the cementitious matter has been entirelydestroyed, in I the process of the present application I preferably boilonly until the cementitious matter has been converted into a readilyfriable condition so that the material can be readily crushedby beingrun between heavy rollers, or by bemg treated in an edge runner mill orsimilar device.

I call attention to the fact that while inthe prior processes, commonlyin use in this country, such as the sulfite process and the sodium sucalled sulfate process). I claim: Y

1. A process which comprises boiling cellulosic and li eous materialwith a dilute aqueoussolution of a soluble nitrate, soaking in water andmechanically reducing to process, the soda fide process (so a pulK. v

2. processwhich comprises boiling cellulosic and ligneous material witha solution of a. nitrate of an alkali-forming metal of substantiallybelow 4% concentration, and continuing the treatment until thecementitious matter is converted into a readily friable condition butnot until the material has been convertedinto a (pulpy mass, thereaftersoaking in-water an ducinito a pulp.

3. process which com rises boiling cellulosic and ligneous matenal witha solution of sodium nitrate, and continuing the treatment until thecementitious matter is converted into a readily friable condition butnot until the material has been converted into a pulpy mass, thereaftersoaking in water and mechanically reducing to a pul mechanically re-.

4. A process which com rises boiling ce lulosic and ligneous materialwith a solution.

of sodium nitrate of about 1 to 4% strength, and continuing thetreatment until the cementitious matter is converted into a readilfriable condition but not until the material has been converted into apulpy mass, thereafter soaking in water and mechanically reducing to apulp.

5. A process which comprises boiling cellulosic and 1i eou's materialwith al to 2% solution 0 a nitrate of an alkali-forming metal, andcontinuing the treatment until the cementitious matter is converted intoa readily friable condition but not until the material has beenconverted into a pul y mass, thereafter soaking in water and mecanically reducing to a pulp.

6. A process which comprises boiling cellulosic and li neous materialwith a 1 to 2% solution 0 a nitrate of an alkali-forming metal, andcontinuing the treatment until the cementitious matter is converted intoi a readily friable condition but not until the material has beenconverted into a pulpy' mass, thereaftercrushing the cooked mate rialand mechanically pulping thesame without subjecting the same to theusual grinding operation pulp.

In testimony whereof I aflix my signature.

, ROBERT A. MARR.

used in making wood

